Matlab Zeros, What type of matrix will I get from this?

Hello, I am trying to understand a code that I using in my project, could someone tell me what do I get from this operation?

scan_trous_carres0=zeros((size_lambda*size_period*size_etching_depth*size_phi),9)

The 9 comes from a column of a text file that where I am getting data, I am trying to figure out why I am I multiplying the values inside the parenthesis and then I have the 9 outisde that parenthesis. What kind of matrix will I get?

[dpb]

Did you try it to see?

Where do the other variables come from would be a hint as to why the expression as well as looking for where the LHS variable is subsequently used.

Or, see what happens if you just define the variables to have some (small) integer values and then try it at command line...I promise it won't start WW III! :)

[dpb]

ADDENDUM:

Or, just set a breakpoint in the debugger and poke around when you get there...

Answer 1

[Adam Danz]

> could someone tell me what do I get from this operation

Assuming your variables are scalar (1 value) or, when multipled, produce a scalar, scan_trous_carres0 will be an mx9 matrix of 0s where m is the result of the multiplication. Try it, as dpb suggested, or read about it in the documentation.

> I am trying to figure out why I am I multiplying the values inside the parenthesis

We certainly don't know why you're doing that 🙂. Apparently those 4 variables describe lengths or sizes of something and your output matrix needs to have that many rows. Are those values scalar? Vectors that, when combined, produce a scalar? We don't know.

This function is commonly used to preallocate loop-variables.

> and then I have the 9 outisde that parenthesis

Well, apparently you need 9 columns of 0s. size(x,y) produces a matrix of 0s of size x*y.

> What kind of matrix will I get?

A matrix of 0s of class double

To confirm,

class(scan_trous_carres0)

[Jose Cuevas]

Thank you, it appears that I was preparing a 2D matrix of 9 columns with a long range of values in x. The values came from a loop in python, it took me a while to connect the dots.